duplicate meshes snap back to original mesh

I have a tree, I copy it and places it in different places in object mode(copies/duplicates…) but shortly after they all return to their original place of origin, that is, stacked upon another. What to do? I ve tried with make single user, but it doesnt fix the problem:(

the original have IPO Loc keys maybe?!

Thanks for the answer, If thats the problem, I would not know how to unlock them??!!!
The thing is, I can duplicate and spread these copies all over my scene, and then make a time sequence/animation, but as soon as I have made a timeline, eg frames 1-200, and then add copies of an already existing mesh, they snap back to the original mesh if I move to a new frame. I have to remove all keys in NLA editor and in F10 settings make sure that animation start: frame one, and animation end: one, so no time sequence, I can then build up my scene again, duplicate, etc. and animate, but again, I can´t add new duplicates, they will snap back:-(

OTO’s not saying that they have locked keys, but that they share the same Loc[ation] IPO curve. When you duplicate an animated object, you’re making a copy of it’s animation also.

This bit from the manual may help:

“If you want to delink the selected object from its Ipo curve, click the X next to the Ipo Name. If you want to make some customizations to the motion of the active object only (and not all the other objects that share this Ipo), you have to make a single user copy of the Ipo curve for this object. To do this, click on the Number of Users button (the 2 in the example above) located on the header next to the name. Blender will prompt you to confirm making a single user copy, and if you confirm, a new Ipo will be created (the name will change) and it will be assigned only to the active object.”

There’s probably more info on this in the pages following that one in the manual as well.

Sir Cire
you perfectly completed my poor answer!
Thank you!